Due to the recent emphasis on heating and cooling economy in order to conserve power and fuel, some of the prior art thermostats have been provided with various different schemes for effecting such economics. For instance, one of the prior art thermostats was operable in a heating mode within a temperature range of about 55.degree. F. to 75.degree. F. and obviated the ability to heat at temperatures in excess of this heating range. Also, this one prior art thermostat was operable in a cooling mode within a temperature range of about 75.degree. to 95.degree. F. and obviated the ability to cool at temperatures less than this cooling range. As a temperature indicating knob was rotated through these heating and cooling ranges to set a selected temperature for the given space in which the prior art thermostat was located, a clutch type device associated with the temperature indicating knob was operable to translate the rotation thereof into adjusting movement of a bimetal element for sensing the temperature of the given space. Thus, the adjusted position of the bimetal was correlative with the temperature set by the temperature indicating knob in the aforementioned heating and cooling temperature ranges. When the temperature indicating knob was rotated between the heating and cooling temperature ranges, the temperature indicating knob transcended an "off" space which was interposed between such ranges, i.e. between the respective 75.degree. F. temperature settings thereof. Of course, as the temperature indicating knob was rotated through the "off" space between the heating and cooling temperature ranges, the clutch type device was actuated so as to interrupt the adjusting movement of the bimetal element in response to the rotation of the temperature indicating knob. Further, upon the rotation of the temperature indicating knob through the "off" space into either of the heating and cooling temperature ranges, a drive arm carried by the temperature indicating knob was drivingly engaged with a cam thereby rotating it in a direction to effect the chosen heating or cooling operating mode of the thermostat. Since the rotational movement of the temperature indicating knob to a temperature setting in either of the heating and cooling temperature ranges automatically effected the operating mode of the prior art thermostat, it is believed that at least one of the disadvantageous or undesirable features of such prior art thermostat was that no manual selection of the operating modes thereof was provided.